Compress PDF

How to make a PDF smaller

Almost always because something will not accept it: a mail server with a ten megabyte limit, a government form that wants two, a job application site that wants one. The document is fine; it is simply too heavy to go where it has to go.

1. Drop the PDF on the box at the top. Its size is shown.
2. Choose Tidy up first. It is safe and sometimes it is enough.
3. Press Make it smaller. You are told what the file became before you are offered anything to save.
4. If that was not enough, choose Rebuild the pages as pictures, pick how hard, and try again.
5. Press Save the PDF when a result is worth keeping.

The choice every compressor hides

There are two different things going on behind the single button other sites give you, and they cost different amounts.

Tidying up rewrites the file’s own bookkeeping, packs its pieces together and drops whatever nothing points at any more - a font left behind by an editor, an old version of a page. Every letter and every picture is left exactly as it was. On a file that has been edited a few times this can take a third off. On a file that was written cleanly the first time it takes nothing off, and this tool says so rather than handing you a file that is no better.

Rebuilding the pages as pictures draws each page and puts the drawing in a new file. It always saves a lot, often nine tenths. It also costs you the text: the words stop being words and become part of a picture, so they can no longer be searched, selected, copied, or read aloud by a screen reader. Right for a scan, which was a picture already. Wrong for a contract somebody has to quote a line from.

Nobody can tell you which to pick without knowing what the document is for, which is why both are here and the cost of each is written down.

How hard to rebuild

Three levels, and what they mean is how many dots per inch the pages are drawn at. Careful stays printable. Small is the right trade for something being emailed and read on a screen. Smallest is for a page that only has to be legible.

Text goes soft before pictures do, because a letter is a thin sharp shape and thin sharp shapes are what squeezing a picture ruins first. If the result looks rough, go up a level rather than down.

What it cannot do

It cannot beat a paid desktop tool that re-squeezes each picture inside the page individually while leaving the text alone. That needs to take apart every picture in the file, and a browser doing that on a large document would sit frozen for minutes. The honest version of that job is not available here.

It also cannot make a file smaller than the pictures inside it. A twenty megapixel photograph pasted into a page is most of the file, and only redrawing the page touches it.